As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
MCN - MAJOR REPAIR - DURING C-18 CHECK CORROSION WAS FOUND AFT CARGO DOOR SILL LOWER CHANNEL AT BS 837, STR 25 RT. MAINTENANCE REMOVED CORRODED AFT CARGO DOOR SILL LOWER CHANNEL AT BS 837, STR 25 RT; FABRICATED A NEW REPLACEMENT CHANNEL PER DWG 65-47957; INSTALLED REPAIR PART IAW B737-300 SRM 51-40-02.